A series is presented of 238 living renal donors who have been followed for periods of from eight months to eight years. Careful selection of donors is mandatory in order to avoid postoperative mortality or morbidity. Anatomic variations which may affect the donor or recipient operations are discussed. There were no deaths, and postoperative complications were usually minor. The most common were atelectasis or pneumonitis or both, pneumothorax, and urinary tract infection. No patients developed permanent renal insufficiency. Compensatory hypertrophy of the remaining kidney resulted in restoration of creatinine clearance and para-aminohippuric acid clearance to two thirds or more of preoperative values. The use of related living donors is justified by the low risk to the donor and the prolongation of life in the recipients.